Not much is known about brain structural change in younger populations and minorities. The cross-sectional relationship between depressive symptomatology and racial discrimination with structural measures of brain tissue volume was investigated using magnetic resonance images for 710 participants in the CARDIA Study in 2010. Those reporting depressive symptoms and racial discrimination had lower total brain matter tissue volume compared to those who reported neither (-8.8 mL; 95% CI: -16.4, -1.2), compared to those with depressive symptoms only (-10...

Purpose in life is potentially a modifiable "health asset" that enhances health and well-being. However, the association between purpose and health in younger populations remains understudied. This study prospectively examined an aspect of purpose in life, specifically having a sense of mission, and a wide range of psychosocial well-being, mental health, health behaviors and physical health outcomes in young adults. Longitudinal data from the Growing Up Today Study (2007 to either 2010 or 2013 questionnaire wave; mean baseline age was 22...

Alterations in the composition of the microbiota have been implicated in many diseases. The Human Microbiome Project (HMP) provides a comprehensive reference dataset of the "normal" human microbiome of 242 healthy adults at five major body sites. The HMP used both 16S ribosomal RNA gene sequencing and whole-genome metagenomic sequencing to profile the subjects' microbial communities. However, accessing and analyzing the HMP dataset still presents technical and bioinformatic challenges, as researchers must import the microbiome data, integrate phylogenetic trees, and access and merge public and restricted metadata...

Phase 1 of the Human Microbiome Project (HMP) investigated 18 body subsites of 239 healthy American adults, to produce the first comprehensive reference for the composition and variation of the "healthy" human microbiome. Publicly-available data sets from amplicon sequencing of two 16S ribosomal RNA variable regions, with extensive controlled-access participant data, provide a reference for ongoing microbiome studies. However, utilization of these data sets can be hindered by the complex bioinformatic steps required to access, import, decrypt, and merge the various components in formats suitable for ecological and statistical analysis...

Correct specification of the exposure model is essential for unbiased estimation in marginal structural models with inverse-probability-of-treatment weights. However, although flexible modeling is commonplace when estimating effects of continuous covariates in outcome models, its use is less frequent in estimation of inverse probability weights. Using simulations, we assess the accuracy of the treatment effect estimates and covariate balance, obtained with different exposure model specifications when the true relationship between a continuous possibly time-varying covariate Lt and the logit of the probability of exposure is non-linear...

Gene-environment (G × E) interaction is important for many complex traits. For a case-control study of a disease trait, logistic regression is the standard approach to model disease as a function of a gene (G), environmental factor, G × E interaction, and adjustment covariates. We propose an alternative model with G as the outcome and show how it provides a unified framework for obtaining all of the common G × E tests. These include the 1-degree-of-freedom (df) test of G × E interaction, the 2-df joint test of G and G × E, the case-only and empirical-Bayes tests, and several two-step tests...

Children with obesity have a cardio-metabolic risk profile that may predispose them to cardiovascular diseases. We examined the associations between childhood body mass index (BMI) levels and changes on the risk of atrial fibrillation and flutter (AFF) in adulthood.We conducted a population-based cohort study of Danish schoolchildren aged 7-13 years born from 1930-1989. Among 314,140 children, 17,594 were diagnosed with AFF as adults. In both men and women, above-average BMIs in childhood were associated with increased risks of AFF...

We explored the association between occupational exposure to extremely low-frequency magnetic fields (ELF-MF) and electric shocks and the risk of amyotrophic lateral sclerosis (ALS) in a pooled case-control study (Euro-MOTOR) from three European countries. ALS patients and population-based controls were recruited in Ireland, Italy and the Netherlands between 2010 and 2015. Lifetime occupational and lifestyle histories were obtained using structured questionnaires. We applied previously developed job-exposure matrices assigning exposure to ELF-MF and potential for electric shocks...

Evidence is required to evaluate the effectiveness of population-level endoscopic screening for esophageal cancer (EC). In this study, 5,632 permanent residents aged 25-65 years from 6 villages of Hua County, Henan Province of China, were defined as the screening cohort and offered intensive endoscopic screening. Residents of all 914 remaining villages in Hua County were included as the control cohort, and age-gender standardization was used to calculate the expected number of EC and upper gastrointestinal cancer cases and deaths in the screening cohort...

Several metals have carcinogenic properties, but their associations with breast cancer are not established. We studied cadmium, a "metalloestrogen", and nine other metals in relation to young-onset breast cancer (diagnosis age <50), which tends to be more aggressive than and have a different risk profile from later-onset disease. We measured recent metal exposure by assessing element concentrations in toenails from 1,217 disease-discordant sister pairs from the US-based Sister (2003-2009) and Two Sister (2008-2010) Studies...

Population-level effects of chlamydia control strategies on chlamydia transmission dynamics are difficult to quantify. In this study, we calibrated a novel sex- and age-stratified pair-formation transmission model of chlamydial infection to epidemiological data in the United States for 2000-2015. We used sex- and age-specific prevalence estimates from the National Health and Nutrition Examination Surveys, case report data from national chlamydia surveillance, and survey data from the Youth Risk Behavior Survey on the proportion of sexually active 15-18 year-old population...

Global surveillance of antimicrobial resistance (AMR) is a key component of the Global Action Plan on AMR. Laboratory-based surveillance is inherently biased and lacks local relevance due to aggregation of data. We assessed the feasibility, sensitivity, and affordability of a population-based AMR survey using Lot Quality Assurance Sampling (LQAS), which classifies a population as having a high or low prevalence of AMR based on a-priori defined criteria. Three studies were carried out in Medan and Bandung, Indonesia between April 2014 and June 2017...

Some forms of cancer screening have the potential to reduce cancer incidence, if the screening modality can identify not only a malignancy but a treatable pre-malignant condition (such as a colon polyp) as well. Cohort studies of the efficacy of these forms of screening in reducing the incidence of cancer face many challenges, notably the difficulty in distinguishing whether a test performed in a given individual was screening or diagnostic in nature. Downward bias in the estimated efficacy of screening resulting from misclassification of test indication is a particular problem in cohort studies that seek to gauge cancer incidence beginning at the time of screening (and a corresponding point in time among unscreened persons)...

Prospective and retrospective studies of vitamin D and breast cancer have produced discrepant results. This may be due to variations in serum 25-hydroxyvitamin D [25(OH)D] concentrations over time, including systematic changes after breast cancer diagnosis. We measured total serum 25(OH)D in Sister Study participants who provided samples at baseline (2003-2009) and 4-10 years later (2013-2015). This included 827 women with an intervening breast cancer and 771 without. Although modestly correlated over time (R=0...

Increasing alcohol outlet density is well-documented to be associated with increased alcohol use and problems, leading to the policy recommendation that limiting outlet density will decrease alcohol problems. Yet few studies of decreasing problematic outlets and outlet density have been conducted. We estimated the association between closing alcohol outlets and alcohol use and alcohol-related violence, using an agent-based model of the adult population in New York City. The model was calibrated according to the empirical distribution of the parameters across the city's population, including the density of on- and off-premise alcohol outlets...

Samoilenko and Lefebvre correctly note two typos in the formulas in the 2011 paper of Ananth and VanderWeele on placental abruption. Fortunately, to the best of our knowledge, researchers are using our methods papers, and our book on mediation analysis, rather than our paper on placental abruption, to carry out their direct and indirect effect analyses; and in our methods papers, and the book, the formulas are correct. The formulas discussed by Samoilenko and Lefebvre, and in our work, make reference to a "rare outcome assumption...

Surveillance data serving for epidemic alert systems are typically fully aggregated in space at the national level. However, epidemics may be spatially heterogeneous, undergoing distinct dynamics in distinct regions of the surveillance area. We unveil this in retrospective analyses by classifying incidence time series. We use Pearson correlation to quantify the similarity between local time series and then classify them using modularity maximization. The surveillance area is thus divided into regions with different incidence patterns...

Much of the healthy worker effect literature focuses on studies of chronic disease and mortality; however, when studying pregnancy outcomes, these effects might differ because of the short, defined risk periods of most pregnancy outcomes. Three pregnancy-specific healthy worker effects have also been described, but the structure of these effects have not yet been investigated when occupational exposure, and not employment status, is the exposure of interest. We used directed acyclic graphs to examine healthy worker effects in studies of occupational exposures and pregnancy outcomes: healthy hire effect, healthy worker survivor effect, desperation/privilege effect (differential workforce re-entry after pregnancy), reproductively unhealthy worker effect (women with live births leave the workforce, women with non-live births do not), and insecure pregnancy effect (women with adverse pregnancy outcomes reduce exposures in subsequent pregnancies)...

There is an association between stress and dementia. However, less is known about dementia among persons with varied stress responses and sex differences in these associations. This population-based cohort study examined dementia among persons with a range of clinician-diagnosed stress disorders, and the interaction between stress disorders and sex in predicting dementia, in Denmark from 1995 to 2011. This study included Danes 40 years or older with a stress disorder diagnosis (n = 47,047) and a matched comparison cohort (n = 232,141) without a stress disorder diagnosis from 1995 through 2011...